Tags, which are used for organizing contents on the Internet, are key words that are highly relevant to a document. The contents of the document may be briefly described and classified by tags to facilitate retrieval and sharing.
At present, there are mainly three manners for adding a tag to a document: 1) a manner of manual tag, in which a specific tag is designated to the document manually; 2) a manner of key word tag, in which an important key word that is automatically abstracted from the document by analyzing the contents of the document is taken as a tag; and 3) a manner of socialized tag, in which a tag is added to a user's document by the user himself. There are problems in all of the three manners, for example, as to 1) the manner of manual tag, tags cannot be added to a large amount of documents automatically; as to 2) the manner of key word tag, only a key word occurring in the document may be chosen as a tag, whereas not all of the key words are suitable to be a tag; and as to 3) the manners of socialized tag, it requires a user to add tags to the document by himself, resulting in disordered tags due to inconsistent standards of different users.